Fans will be disappointed by a lack of imagination in Jance's ( Until Proven Guilty ) latest mystery featuring J. P. Beaumont, hard-drinking detective. When he checks into an alcohol and drug rehabilitation center in rural Arizona, the bad-tempered Beaumont is paired with an annoying roommate, Joey Rothman, who sneaks out after curfew to deal drugs and seduce girls. After spying his own visiting teenaged daughter smooching with Joey, Beaumont waits up for him with fists bared, joined by the irate father of a young patient whom Joey has impregnated. When Joey's body is found hanging from a tree, apparently plugged dead with Beaumont's gun, the police peg Beaumont along with the pregnant girl's father as their prime suspects. The two men team up with Joey's mother to find the killer. Beaumont, throughout, spouts cliches: ``Her look of utter abandonment sliced through my heart like a hot knife.'' Despite a few dramatic mountainside car chases and fights with machine-gun-toting drug thugs, Jance's plot is plodding, disjointed and predictable. (Apr.)